JP2002046158A - Mold for injection molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold for injection molding which can mold a rein product having an uneven part on the inner surface precisely and efficiently. SOLUTION: In the mold for molding the undercut resin product P having the uneven part Q fitted in the mold extraction direction to the inner surface p1 of a hollow part p, a male mold part 30 for forming the hollow part p is composed of a center core 1 and a main side core 2 and a sub-slide core 3 which are arranged alternately on the periphery of the center core 1, the main slide core 2 and the sub-slide core 3 have uneven outer surfaces 2c and 3c corresponding to the uneven part Q of the inner surface p1 of the resin product, the center core 1 alone retreats to form the first vacant part A1, the main slide core 2, after sliding to the center side of the first vacant part A1, retreats with the center core 1 to form the second vacant part A2, and the sub-slide core 3 slides to the center side of the second vacant part A2 to enable the injection of the resin product P.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal mold for injection molding an undercut synthetic resin product having an uneven portion on an inner surface.

[0002]

2. Description of the Related Art In molding an undercut resin product having an uneven portion on an inner surface, a male portion is locked on the uneven portion.
Various measures have been devised so that the male mold part is divided and the mold part is reduced to a smaller diameter than the concave and convex part and can be released. For example, JP-B-53-42618, JP-B-59-14333, JP-A-59-150715, and JP-A-59-3
As disclosed in JP-A-8032, the male part is composed of a conical core core, a first wedge-shaped core and a second wedge-shaped core arranged on a slope of the core core, and the first wedge-shaped core is centered with the retraction of the core core. After collecting and releasing the mold, there has been proposed a method in which the second wedge-shaped core is assembled and released from the space created by the release of the first wedge-shaped core.

[0003]

In a mold in which a first wedge-shaped core and a second wedge-shaped core are arranged on a slope of a conical core, the first and second wedge-shaped cores follow the retraction of the core. Therefore, when the core core is retracted, it is necessary to press the core core so as not to move in the retreating direction. Moreover, when the molten resin penetrates to the slope of the core core and solidifies, there is a problem that sliding of the wedge-shaped core is hindered. Then, this invention was made in view of such a problem which a prior art has, and it aims at the high precision of the resin product which has an unevenness | corrugation part in an inner surface, and can also shape it efficiently. An object of the present invention is to provide a mold for injection molding.

[0004]

In order to achieve the above-mentioned object, an injection molding die according to the present invention is an undercut resin product having a concave and convex portion on an inner surface of a hollow portion to be engaged in a die-cutting direction. In the molding die of the male mold portion forming the hollow portion,
It is composed of a center core, a main slide core and a sub slide core which are alternately arranged on the outer periphery of the center core, and the main slide core and the sub slide core each have an uneven outer surface corresponding to the uneven portion of the resin product inner surface. , The center core recedes alone to form a first space, and the main slide core slides toward the center of the first space, and then recedes together with the center core to form a second space, and the sub-slide The core slides toward the center of the second space to enable injection of the resin product.

Here, the hollow portion of the resin product refers to a portion that opens to one side or a portion that opens to both sides and penetrates. The shape is not limited to a circular shape, and includes a non-circular shape. The term “all parts”, such as concave parts and convex parts, screw parts, etc., engages with the mold at the time of die removal. Here, the male part refers to one that forms the inner surface of the resin product and is inserted into the hollow part, and the center core is disposed at the center of the male part,
The main slide core and the sub slide core are the ones that retreat first when the mold is opened.The main slide core and the sub slide core are alternately arranged on the outer periphery of the center core, slide sequentially toward the center as the center core retreats, and separate from the resin product. Say what you type. Here, the first vacant space refers to a region generated when the center core is retracted, and the second vacant space refers to a region generated when the main slide core and the center core are retracted.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the shape of an undercut resin product will be described with reference to FIG. 9 (a). The resin product P has a hollow portion p opened on one side and an uneven portion Q is formed on an inner surface p1. As shown in FIG. 1, the injection mold used for molding the resin product P is composed of a fixed mold 10 and a movable mold 20 which can be separated from the fixed mold 10. The mold 10 includes a cavity plate 16 that forms the outer surface p2 of the resin product P. The movable mold 20 includes the stripper plates 9, 19, the core plate 5, and the back plate 6, the center core 1, the main slide core 2, and the sub slide. A male mold part 30 comprising a core 3, wherein a cavity is formed by the cavity plate 16 and the male mold part 30;
When the movable mold 20 is retracted, first, the cavity plate 16
The core plate 5 and the back plate 6 are separated from each other, and then the core plate 5 and the stripper plate 9,
19 are separated.

Next, a first embodiment of an injection mold according to the present invention will be described with reference to FIGS.
Is formed of a center core 1, a main slide core 2 and a sub slide core 3 alternately arranged on the outer periphery of the center core 1, and the main slide core 2 is provided with an uneven portion on the inner surface p <b> 1 of the resin product. The main uneven outer surface 2c corresponding to Q, the sub-slide core 3 is provided with a sub-irregular outer surface 3c continuous with the main uneven outer surface 2c, and the center core 1 is independently receded to form a first empty space A1. After the slide core 2 slides toward the center of the first space A1 generated by the retreat of the center core 1 and separates from the resin product inner surface p1, it retreats together with the center core 1 to form a second space A2, Secondary slide core 3
Slides toward the center of the second empty space A2 generated by the retreat of the main slide core 2 and the center core 1 and separates from the resin product uneven portion Q, thereby enabling the injection of the resin product P.

The center core 1 protrudes from the center in the radial direction as shown in FIG. 10, has a receiving portion 1b for the main slide core 2 on the outer peripheral side, and attaches the retreating side to the back plate 6 as shown in FIG. The support portion 1a has a support width S and protrudes in four directions. For convenience, the support portions 1a are first to fourth support portions 11, 12,.
13, 14. As shown in FIG. 5, the main slide core 2 comes into contact with each of the first to fourth support portions 11, 12, 13, and 14. For convenience, the first to fourth main slide cores 21, 22, 23,. 24, the sub slide core 3 is fitted between the first to fourth support portions 11, 12, 13, and 14, respectively. For convenience, the first to fourth sub slide cores 31, 32, 33, and 34 are used. And

The main slide core 2 is, as shown in FIG.
A main base part 2a held on the front side of the core plate 5 and a main core part 2b inserted into the hollow part p of the resin product P are provided at substantially right angles, and the core width S is the same width as the support part 1a of the center core 1. The slide device 8 is engaged with the main base 2a as shown in FIG. 3 and is slidable in a direction perpendicular to the longitudinal movement of the center core 1. The first to fourth main slide cores 21, 22, 23, 2
4 are separated from the resin product inner surface p1 in the orthogonal direction, are gathered on the center side of the first empty space A1, and can be released in the assembled state.

As shown in FIG. 11B, the auxiliary slide core 3
A sub-base 3a to be held on the front side of the core plate 5 and a sub-core 3b to be inserted into the hollow part p of the resin product P are provided at a substantially right angle, and the sub-core 3b has an uneven outer surface 3c as an outer edge. 90
The first side face 3d is, for example, on one side face of the first support portion 11 and the first main slide core 21, and the other side face 3e is on the second side.
The slide device 18 which abuts on the support portion 12 and the other side surface of the second main slide core 22 and engages with the sub base 3a as shown in FIG.
The sub core 3b slides toward the center of the second space A2 generated by the retreat of the center core 1 and the main slide core 2 in the direction perpendicular to the forward and backward movement of the center core 1. , The first to fourth sub slide cores 31, 3
2, 33, 34 approach the center side of the second empty space A2, and separate from the resin product inner surface p1 in the orthogonal direction.

The slide dimension L of the main slide core 2 and the sub slide core 3 is the same as the inside / outside difference T between the maximum internal dimension R and the minimum internal dimension r of the hollow portion p, that is, the internal / external difference T of the uneven portion Q.
Alternatively, the main slide core 2 is slightly larger than the inner / outer difference T,
In addition, it is desirable that the sub-slide core 3 not be locked with the uneven portion Q of the resin product P when the sub-slide core 3 is retracted. Also, the first
When the fourth to fourth main slide cores 21, 22, 23, 24 are assembled at the center of the first space A1, they are still inserted between the first to fourth sub slide cores 31, 32, 33, 34. Is desirable.

Since the injection mold of the first embodiment has the above structure, the main slide core 2 of the male mold part 30 and the auxiliary slide core 2 of the male mold part 30 are closed when the fixed mold 10 and the movable mold 20 are clamped as shown in FIG. The slide cores 3 are alternately located on the outer periphery of the center core 1 as shown in FIG.
c and the sub-projection outer surface 3 c of the sub-slide core 3 are continuous, and a cavity of the resin product P is formed between the sub-slide core 3 and the cavity plate 16.

After the molten resin is injected into the cavity and the molten resin is solidified, the movable mold 20 is first opened, and only the center core 1 of the male mold portion 30 is retracted as shown in FIG. Accordingly, a first empty space A1 is formed on the inner peripheral side of the main slide core 2 and the sub slide core 3. Next, the main slide core 2 is slid to the center side of the first space A1 by the slide device 8, and the main core 2b of the first to fourth main slide cores 21, 22, 23, 24 is made uneven as shown in FIG. After separating from the part Q and assembling, the first to fourth main slide cores 21, 22, 23 and 24 assembled as shown in FIG. 4 are retracted together with the center core 1 and completely released from the resin product P.

After the second empty space A2 is formed by the retreat of the center core 1 and the main slide core 2, the first to fourth sub slide cores 31, 32, 33, 34 as shown in FIGS.
Is slid toward the center of the second empty portion A2, the sub core 3b of the first to fourth sub slide cores 31, 32, 33, and 34 is detached from the uneven portion Q of the resin product P. The injection of the product P becomes free.

The second embodiment will be described with respect to differences from the first embodiment. As shown in FIG. 12, a center core 1 projects a support portion 1a having a support width S in three directions at intervals of 120 degrees.
The first to third main slide cores 21, 22, and 23 having the same width as the support width S are respectively disposed on the support portions 11, 12, and 13, and between the support portions 11 and 12, between the support portions 12 and 13, And the first to third auxiliary slide cores 3 between the support portions 13 and 11.
1, 32, and 33, and each of the sub-slide cores 31, 32, and 33 has approximately 12
Since it has a fan shape of 0 degrees and the other structure is the same as that of the first embodiment, the description is omitted.

The third embodiment will be described with respect to differences from the first embodiment. As shown in FIG. 9 (b), a hollow portion p is provided in a penetrating state, and irregularities bulging outward in the middle of an inner surface p1. This is a mold for injection molding of a resin product P having a portion Q. As shown in FIG. 13, the mold for injection molding is a main base 2a of the main slide core 2 and a sub base of the sub slide core 3 constituting the male mold part 30. 3a respectively form the concave and convex outer surfaces 2c and 3c corresponding to the concave and convex portions Q of the resin product inner surface p1. The other structure is the same as that of the first embodiment, and the description is omitted.

[0017]

The main slide core 2 and the sub slide core 3 are divided into three parts in the second embodiment and four parts in the first embodiment, but are not limited to three parts and four parts. Division into six divisions is also possible. Further, the sliding means for the main slide core 2 and the sub slide core 3 is not limited to the above example, and the main base 2a of the main slide core 2 and the sub base 3a of the sub slide core 3 are If held at 17, the slides of the main slide core 2 and the sub slide core 3 become more stable. Fixed mold 2
The release of 0 can be performed before and after the retraction of the center core 1, or can be performed before and after the retraction of the main slide core 2 and the sub slide core 3. Fixed mold 10
The configuration of the movable mold 20 and the movable mold 20 is not limited to the above embodiment, and the center core 1, the main slide core 2, and the sub slide core 3 constituting the male mold portion 30 are formed according to the shape of the resin product P. It can be changed as appropriate.

[0018]

The injection mold according to the present invention has the same structure as described above, and has the following effects. After alternately arranging the main slide core and the sub slide core on the outer periphery of the center core, the main slide core is gathered on the center side of the first empty space generated by the retreat of the center core and separated from the uneven portion of the product, Since the core and the assembled main slide core are retracted, and the auxiliary slide core is separated from the center of the second space later, when the center core is retracted,
There is no need to press the main slide core and the sub slide core, so that the structure is simplified, the mold can be easily disassembled and assembled, and it can be provided at low cost. Moreover, since no stress in the mold release direction acts on the uneven portion on the inner surface of the resin product, the undercut product can be molded with high precision and without damage. Further, since the main slide core and the sub slide core slide individually, even if the molten resin enters between the cores and solidifies, it can be easily removed in a release state.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a schematic structure of an injection mold according to the present invention.

FIG. 2 is a cross-sectional view of a main part of the first embodiment at an initial stage of mold opening.

FIG. 3 is a sectional view of a main part when the main slide core is released from the mold.

FIG. 4 is a cross-sectional view of a main part when the auxiliary slide core is released from the mold.

FIG. 5 is a schematic plan view of a movable mold.

FIG. 6 is a sectional view of a main part of a male mold part at the time of mold clamping.

FIG. 7 is a sectional view of a main part of the male mold part when the main slide core is released from the mold.

FIG. 8 is a cross-sectional view of a main part of the male mold part when the auxiliary slide core is released from the mold.

9A and 9B are longitudinal sectional views of a resin product.

FIG. 10 is a plan view of a center core.

11A and 11B are perspective views of a main slide core and a sub slide core.

FIG. 12 is a sectional view of a main part of a male mold part at the time of mold clamping according to a second embodiment.

FIG. 13 is a sectional view showing a schematic structure of an injection mold according to a third embodiment.

[Explanation of symbols]

1 center core 1a, 11,12,13,14 support part 2,21,22,23,24 main slide core 2a main base part, 2b main core part, 2c main uneven outer surface 3,31,32,33,34 Slide core 3a Secondary base, 3b Secondary core, 3c Secondary uneven outer surface 5 Core plate 6 Back plate 7, 17 Pressing plate 8, 18 Slide device 16 Cavity plate 9, 19 Stripper plate 10 Fixed mold, 20 Movable mold, 30 Male part A1 first empty part, A2 second empty part P resin product, p hollow part, p1 inner surface, p2 outer surface,
Q Uneven part L Sliding dimensions of main slide core and sub slide core S Support width and core width R Maximum internal dimension, r Minimum internal dimension T Difference between inside and outside of uneven part

Claims (1)

[Claims] 1. A molding die for an undercut resin product (P) having a concave / convex portion (Q) on the inner surface (p1) of the hollow portion (p) in the die-cutting direction. ) Is formed of a center core (1), a main slide core (2) and a sub slide core (3) alternately arranged on the outer periphery of the center core (1). The slide core (2) and the sub-slide core (3) are provided with an uneven outer surface (2c, 3) corresponding to the uneven portion (Q) of the inner surface (p1) of the resin product.
c), wherein the center core (1) retreats independently to form a first empty space (A1), and the main slide core (2) slides toward the center of the first empty space (A1). After that, the second slide part (A2) is formed by retreating together with the center core (1), and the sub-slide core (3) slides toward the center of the second space part (A2) to make the resin product (P). A mold for injection molding, characterized in that injection of a mold is enabled.